Add rpath flag to LDFLAGS if supported.
Fixes PR pkg/49021

Bump PKGREVISION.
Updated www/ap2-python to 3.5.0nb1
fix missing distinfo entry for tar-1.27.1.tar.bz2
Fix NetBSD and Solaris atomic_dec_and_test.
Based on similar patch for xsrc from Taylor R Campbell.

Bump PKGREVISION.
Updated x11/libdrm to 2.4.54nb1
Move compiler check last, allow to overwrite GCC_REQD in included files.
PR pkg/48985.
Move compiler check to last, allow to set GCC_REQD in somewhere else before.
PR pkg/48981.